1. The Field of the Invention
The present invention relates to compositions and methods of manufacture of an improved skim or lowfat milk product. In particular, the preferred embodiment of the invention relates to compositions and methods of manufacture of a textured type of skim or lowfat milk which is produced by treating skim or lowfat milk with a milk coagulant to partially coagulate and aggregate proteins in the milk. The enzyme-treated milk is then heat processed in order to denature the coagulating enzyme. The finished milk product is then cooled to and stored at an appropriate refrigeration temperature. The final product not only has an increased creamy mouthfeel, but also is characterized by a white color and taste sensations similar to milk with a higher fat content.
2. The Background Art
Milk is a unique product obtained by the secretion of the mammary glands of mammals and is intended for nutrition of the young. Milk provides those nutrients on which many living organisms depend for continued health and growth. The consumption of milk in the United States has become an important aspect of human nutrition. Moreover, because most individuals like the taste of milk, its presence in the marketplace is demanded.
Unfortunately, milk products are generally high in fat content. Americans are becoming increasingly selective about the milk products they consume because of the health problem in later life often associated with the consumption of large quantities of fat. The presence of large amounts of fats in the human body can lead to the deposit of the fats in the arteries. Arterial fat deposits can restrict the circulation of blood which can cause strokes and heart attacks.
At the same time that the public has requested healthier alternatives to presently available milk products, the public has been unwilling to give up flavor or quality in taste of milk products having a high fat content. Generally, even if one milk product is healthier than another milk product, many individuals will eventually return to the milk product which is of a greater quality in terms of taste and flavor. If one type of milk product contains less fat than another milk product, while maintaining acceptable taste, consumers will generally prefer the lower fat-containing product. Indeed, milk products which provide healthy alternatives to the public are eagerly being sought.
Traditionally, the processing of milk results in a change in the composition of the milk. One of the most important processing steps is heating of the milk in order to control the presence of microorganisms. Generally, as the temperature of the milk is increased, microorganisms present in the milk will become deactivated and heat killed.
Heat treatment may be applied to impart other desirable properties. In some products, changes in flavor, color, or viscosity caused by heating may be desired. Heating prior to sterilization may increase the stability of milk proteins to coagulation by subsequent high heat treatments.
The change in flavor from heat treatment of milk proceeds to a "cooked" flavor as the milk temperature increases. This is due to free sulfhydryl groups formed at temperatures above 60.degree. C. The milk then changes to a sterilized milk flavor as the temperature of the milk increases. This is due to the formation of lactones and methylketones from fats.
Still another important processing step is the separation of the milk to yield skim milk and cream. Skim milk has a very low fat content, less than about 0.05%, and this is the milk most health-conscious individuals consume. Nevertheless, skim milk is appropriately berated because of its weak taste and watery mouthfeel. By mixing skim milk and cream, milk may be standardized to a desired fat content to produce the milk products commonly known to most consumers as "1%," "2%," and "whole milk."
The separation of milk to yield skim milk, and even lowfat milk such as 1%, and cream results in the loss of most of the texture or viscosity experienced by the consumption of whole milk. Individuals have submitted that skim milk has a "watery" mouthfeel (i.e., no consistency) due to the absence of fat in the milk (milkfat) in the fluid. Also, the weak flavor and watery color of skim milk is unappealing both to one's taste buds and aesthetic appreciation. Therefore, conventionally prepared and processed skim milk is considered undesirable to the consumer in taste and flavor. Many consumers find the lowfat, 1% or 2% milks also to be unappealing.
Some individuals have attempted to provide a nonfat milk product without the watery texture and taste due to the absence of milkfat in the fluid. Such attempts have involved the addition of nonfat solids into the milk product to provide for some type of texture. The addition of nonfat solids, however, has not met with widespread consumer approval.
Nonfat dry milk powder has been added to fluid skim milk in order to increase the total milk solids of the product. In essence, the nonfat milk solids added in a powder form are similar to the milk solids found in the fluid skim milk. The relative percentages of the constituents of nonfat dry milk powder are in the same relative percentage range as the same constituents in fluid milk.
By adding nonfat dry milk powder to fluid skim milk total protein content, total lactose content, total ash (mineral) content, and total micronutrient content, (e.g., vitamins) all increase to produce a skim milk product with increased total milk solids but with the same relative percentages of each milk constituent (based on dry matter). This process does not lead to consumers being able to perceive an enhanced creaminess or improved mouthfeel sensations because all the milk constituents are in their native (unaltered) state, which does not affect mouthfeel or taste sensations on the tongue.
Other attempts have involved the introduction of fat substitutes into the dairy products. The addition of such fat substitutes gives the impression that fat has been added to the milk product. One commercialized fat substitute product known in the art, produced by such a process, is commonly referred to as SIMPLESSE.RTM., manufactured by The NutraSweet Corporation. The fat substitute SIMPLESSE.RTM. involves the microparticularization of whey or egg proteins. These proteins are heated, stressed, and restructured, resulting in protein structures that are globularized.
Although a food product produced according to the foregoing process provides a food product which does fool the tongue of consumers without the presence of fat, the process is not without its disadvantages. In particular, the converted proteins presented by the process can only be placed in cold food or dairy products such as ice cream. If placed in heated products, the converted proteins revert to an altered state and do not provide the texture strived for in the milk product.
The restrictive nature of these temperature-sensitive products is immediately apparent. Although cold milk products such as ice cream are popular, the use of milk as an ingredient in cooked foods is considerable. A milk product which reverts to an untextured and tasteless composition when commonly placed in a heated condition is disadvantageous.
Further disadvantages of food products prepared by introduction of fat substitutes include the significantly increased price to the finished food product, the possible need for warning statements to prevent warming of the food product, and the fact that fat substitutes are food additives that require FDA approval and specific labeling requirements. Additionally, the fat substitutes contain caloric value (protein-based fat substitutes contain 4 calories per gram--as does normal protein in foods) which increases the total calories of the finished food product.
In light of the foregoing, it is clear that all of the problems present in the lowfat and particularly skim milk area have not been solved. A market is available for a textured skim milk or lowfat milk which solves these additional problems not remedied by currently known skim or lowfat milks. A need, therefore, exists in the art for compositions of and methods for making a skim or lowfat milk product which is textured so that individuals will believe they are drinking milk with a fat content greater than normal skim or lowfat milks.
A need also exists in the art for compositions of and methods for making a skim or lowfat milk product which fools the tongue of an individual without adding unwanted fats or fat substitutes to the milk product.
Additionally, a need exists in the art for compositions of and methods for making a skim or lowfat milk product having greater consumer acceptability because of the increased creaminess, color, mouthfeel and taste sensations similar to a milk with a higher fat content.
Further, a need exists in the art for compositions of and methods for making a skim or lowfat milk product which is not temperature sensitive so that it can be used as an ingredient in cooking.
Still further, a need exists in the art for compositions of and methods for making a skim or lowfat milk product wherein individuals receive the health benefits from the consumption of milk without a sacrifice due to the presence of fats.
A need also exists in the art for compositions of and methods for making a skim or lowfat milk product having a color and appearance similar to milks with higher fat content.
A further need exists in the art for compositions of and methods for making a skim or lowfat milk product wherein the caloric value is not increased and taste is not diminished.